Navigational systems are used to map out routes from a starting point to a destination point. Routes are generally created from a list of road links or nodes. A typical navigational system offers a user several choices for which route to take. These choices generally include the shortest distance, the quickest transit time, or the least expensive (e.g., toll avoidance).
Navigational systems can create routes based on the shortest distance or time in part due to algorithms such as the traveling salesperson problem or other optimization. Navigational systems may also provide additional information such as landmarks and or traffic conditions (for example lights/stop signs etc.). Navigational systems contain millions of road links and nodes from which routes may be generated. The number of routes that are possible is impossibly large.